Hematophagous parasites and the diseases they transmit are an increasing problem in animal husbandry and human health. Hematophagous parasites include ecto-parasite species, such as the tick, mite, flea, mosquito, midges, oestridae (bot flies), hypodermae (warble flies) and endo-parasite species, such as worms, e.g. liver flukes, filarial and tape worms.
In particular, infestations of hard bodied ticks (Ixodes in Europe and North America and Amblyomma and Dermacentor in North America) can affect a variety of animals, including, but not limited to sheep, deer, mice and red grouse. Grouse and other ground nesting birds such as Curlew, Golden Plover and Lapwings especially young birds are highly susceptible to tick burdens and tick borne diseases (TBDs). Therefore, tick infestations present a significant problem in economic, animal welfare and human health terms on moorland habitats.
Ticks often carry one or more diseases and often transmit such diseases from one host to another. It some populations around 40% of the ticks sampled carry one or more tick borne pathogens (there are 19 affecting humans, mammals and birds in Europe alone). In humans ticks may transmit a variety of diseases such as Lyme disease, Human Granulocytic Anaplasmosis and in dogs, Babesia (Red Water Fever).
The life cycle of the tick is complex. Ticks feed on a wide range of hosts. At the larval and/or nymph stage, the male or female tick larvae or nymph will feed on small mammals, rodents as well as larger hosts such as deer, sheep, companion animals and humans. In the adult stage, only the female tick will blood feed and generally will feed normally on larger animals, mammals, such as deer, hare and sheep or birds such as grouse. Once the adult female has fed, she will lay her eggs and die if she has mated. Importantly, when the female takes a blood feed the blood stream of the host passes through the tick and hence a tick borne disease may be more easily transmitted that with other hematophagous parasites, such as fleas or mosquitoes.
The problems caused by ticks are increasing. In the USA in 2007 there were 57,000 confirmed cases of Lyme Disease in humans alone and many other cases of tick borne disease (TBD). Indeed, the UK has seen its first case of tick borne encephalitis in 2008. Lyme disease, which is one of the most common tick borne diseases in humans, is classified as an emerging infectious disease (EID), that is, an infectious disease whose incidence has increased in the past 20 years and threatens to increase in the near future.
There are numerous tick killing or repelling treatments available, but none are satisfactory in that they are either considerably toxic to one or more of the species threatened by tick borne diseases. For example sheep are normally dipped in organophosphorous sheep dips. However such compounds are very toxic to humans, as they travel easily through the skin. More recently synthetic pyrethroids have replaced organophosphorous compounds, as they are much less harmful to humans. However, it is known that synthetic pyrethroids cause environmental damage to fresh water invertebrates, such as beetles, dragonflies, crayfish and the like. With both organophosphorous and synthetic pyrethroid dips, drenches and pour ons there are issues over long term efficacy and withdrawal periods before meat enters the human food chain. This is particularly important when considering ‘wild meat’ such as deer and grouse. There are also general concerns over long term efficacy.
It is desirable to provide a systematic remedy, since topical applications may provide efficacy for a limited period of time. However, known systemic remedies often cause vomiting in animals when administered enterally.
More recently attempts have been made to produce herbal tick remedies. For example, UK Patent Application No. 2448870 describes herbal tick remedies comprising, significant amounts of Allium sativim (garlic) and Juglans nigra folia (black walnut); as well as Picraena excelsa (Quassia), Foeniculum vulgare (fennel) and Azadirachta indica folium (Neem). More specifically, UK Patent Application No. 2448870 describes a herbal tick remedy consisting of a composition with the following ingredients, wherein the relative ratios are shown in brackets, Allium sativim (garlic)(2), Juglans nigra folia (black walnut)(2), Picraena excelsa (Quassia)(1), Foeniculum vulgare (fennel)(1) and Azadirachta indica folium (Neem)(1).
It is clear for example that in the trials exemplified in example, UK Patent Application No. 2448870 the herbal tick remedy may be effective in the brown hare, but not in red deer, where it is seen to be either ineffective or have a deleterious effect. Furthermore, later trials with these formulations have shown that efficacy is not sustained beyond 8 months.
Therefore, there remains a need for an environmentally friendly tick remedy which does not suffer from the disadvantages hereinbefore described.